Explain how an alternating welding current can be converted to a direct current.
What will be an ideal response?
Alternating welding current can be converted to direct current by using a series of rectifiers. A rectifier allows current to flow in one direction only. If one rectifier is added, it would be difficult to weld. A series of rectifiers, known as a bridge rectifier, can modify the alternating current.
Rectifiers become hot as they change AC to DC. They must be attached to a heat sink and cooled by having air blown over them. The heat produced by a rectifier reduces the power efficiency of the welding machine. At the same dial settings for AC and DC, the DC is at a lower amperage. The difference in amperage (power) is due to heat lost in the rectifiers. The loss in power makes operation with AC more efficient and less expensive compared to DC.
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Answer the following statement(s) true (T) or false (F)
1. The flat track repair can be made using either pieces of track from a similar type of board that has been scrapped or from commercial pieces of plain or tinned copper. 2. When the break is in excess of 1/8" (3.18 mm), it is recommended that the track being repaired be cut at 45°. 3. It is more difficult to hold a round wire in place onto a rounded surface. By slightly flattening the wire with serrated needle-nosed pliers, it will be easier to hold the wire in place. 4. The funnellette provides the most reliable type of repair for a double-sided board. 5. The soldering process should include the flow of solder from the lead to the eyelette to the pad, on both sides of a double-sided board.
Type NMS cable contains _____.
a. power wiring only b. communications wiring only c. power, communications, and signaling wiring d. communications and signaling wiring only
____________________ or ____________________ are the procedures used to fasten metal pieces
together by melting a second metal between the two pieces.
Fill in the blank(s) with the appropriate word(s).The bob weight must equal weight of the oil between the journal and bearing, plus the ________
A) Weight of all the pistons B) Rotating weight C) A percentage of the reciprocating weight D) Both B and C